1. Field of the Invention
The present invention relates to a robot and its control method.
2. Related Art
In the conventional art, the robot searches for information concerning an obstacle around the robot by using an outside world sensor such as an ultrasonic wave sensor or a range finder. If an unexpected obstacle is detected, the robot operates to avoid the obstacle while decelerating (see, for example, JP-A 2005-310043 (KOKAI)). If the obstacle proves to be a traveling object, the robot assumes an action strategy of continuing to stop until the traveling object disappears from the vicinity of the robot (see, for example, JP-A 3-282711 (KOKAI)).
The robot observes a time change value of the information obtained from the outside world sensor in order to determine whether the obstacle is a traveling object. By in addition conducting image processing such as template matching or optical flow using a camera, the robot makes a decision whether the obstacle is a traveling object or makes a decision whether the obstacle is a human being in some cases. However, more detailed sorting and analysis are hardly conducted.
An obstacle discrimination technique utilizing height information of the obstacle is also known (see, for example, JP-A 2004-326264 (KOKAI)). According to the technique described in JP-A 2004-326264 (KOKAI), however, the height information is used to detect a stationary environmental obstacle, such as a wall or a pillar, or a human being. In JP-A 2004-326264 (KOKAI), a technique for detecting the posture state of a human being is mentioned, but discrimination of the human being including the degree of caution is not taken into consideration. Furthermore, JP-A 2004-326264 (KOKAI) discloses an obstacle detection and discrimination technique, and a concrete operation change technique against the obstacle is not presented.
Introduction of autonomous traveling objects such as robots into stores is under study. Considering the introduction of robots into general environments such as stores or facilities, however, it becomes important to ensure safety of the robots. Especially in the environment in the state of coexistence with human beings, it is necessary to take safety operation for human being's recognition and human beings who perform recognition. On the other hand, it is also necessary to ensure the basic performance, such as smooth traveling operation, of the robots, and trade off between the safety and the traveling performance occurs.
When a robot has detected a human being, the robot stops on the spot and waits for the human being to go away from the vicinity of the robot, or the robot avoids the with a sufficient spacing between, under present conditions. In a narrow place such as a store, however, it is difficult to ensure a sufficient spacing and consequently the robot cannot help stopping and letting the human being go past. In such an operation strategy, however, the work efficiency of the robot is poor and the robot cannot withstand practical use.
As one of reasons why only such a control technique can be used, it can be mentioned that information concerning other traveling objects the robot can know is little and an action control law which can be applied to all detected persons is used.